Using radio-based Wireless Fidelity (or Wi-Fi, a trademark of the Wi-Fi Alliance) sources to perform indoor positioning has attracted increased attention in the recent. These Wi-Fi sources include mobile devices, such as smartphones. However, building an accurate and stable indoor positioning system remains a challenging task.
One reason that this is a challenging task is that radio signals propagate in a complicated manner and are often affected by noise and other sources. This can result in unstable and noisy signal strength readings. Another reason that makes this takes challenging is that physical characteristics in an indoor setting (such as walls, furniture, computers, and elevators) can affect the Received Signal Strength Indication (RSSI). In addition, movement of persons within the indoor environment can also adversely affect the RSSI. Another factor adding to the challenge is that human indoor movement tends to be less predictable and endures less physical constraints as compared to vehicles on highways.